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A Computational Study of Plume Modeling For Space Launch System Abort Scenarios

This extended abstract details work on Space Launch System (SLS) core stage drag during abort scenarios that is currently being conducted. In the final paper, viscous computational fluid dynamic simulations will be used to study the axial force coefficient on the SLS core stage as a function of its distance to the upstream crew module and launch abort system, the freestream conditions, and the chemical model used to represent the launch abort system abort motor and attitude control motor plumes. In addition, the computational expense of each method will be studied in order to help determine the appropriate trade-off between fidelity and simulation turn around time.

CFD↗

NASA NTRS2015

Orion Launch Abort System Performance During Exploration Flight Test 1

The Orion Launch Abort System Office is taking part in flight testing to enable certification that the system is capable of delivering the astronauts aboard the Orion Crew Module to a safe environment during both nominal and abort conditions. Orion is a NASA program, Exploration Flight Test 1 is managed and led by the Orion prime contractor, Lockheed Martin, and launched on a United Launch Alliance Delta IV Heavy rocket. Although the Launch Abort System Office has tested the critical systems to the Launch Abort System jettison event on the ground, the launch environment cannot be replicated completely on Earth. During Exploration Flight Test 1, the Launch Abort System was to verify the function of the jettison motor to separate the Launch Abort System from the crew module so it can continue on with the mission. Exploration Flight Test 1 was successfully flown on December 5, 2014 from Cape Canaveral Air Force Station's Space Launch Complex 37. This was the first flight test of the Launch Abort System preforming Orion nominal flight mission critical objectives. The abort motor and attitude control motors were inert for Exploration Flight Test 1, since the mission did not require abort capabilities. Exploration Flight Test 1 provides critical data that enable engineering to improve Orion's design and reduce risk for the astronauts it will protect as NASA continues to move forward on its human journey to Mars. The Exploration Flight Test 1 separation event occurred at six minutes and twenty seconds after liftoff. The separation of the Launch Abort System jettison occurs once Orion is safely through the most dynamic portion of the launch. This paper will present a brief overview of the objectives of the Launch Abort System during a nominal Orion flight. Secondly, the paper will present the performance of the Launch Abort System at it fulfilled those objectives. The lessons learned from Exploration Flight Test 1 and the other Flight Test Vehicles will certainly contribute to the vehicle architecture of a human-rated space launch vehicle.

McCauley, Rachel↗

NASA NTRS2015

Orion Launch Abort System Performance on Exploration Flight Test 1

This paper will present an overview of the flight test objectives and performance of the Orion Launch Abort System during Exploration Flight Test-1. Exploration Flight Test-1, the first flight test of the Orion spacecraft, was managed and led by the Orion prime contractor, Lockheed Martin, and launched atop a United Launch Alliance Delta IV Heavy rocket. This flight test was a two-orbit, high-apogee, high-energy entry, low-inclination test mission used to validate and test systems critical to crew safety. This test included the first flight test of the Launch Abort System preforming Orion nominal flight mission critical objectives. NASA is currently designing and testing the Orion Multi-Purpose Crew Vehicle (MPCV). Orion will serve as NASA's new exploration vehicle to carry astronauts to deep space destinations and safely return them to earth. The Orion spacecraft is composed of four main elements: the Launch Abort System, the Crew Module, the Service Module, and the Spacecraft Adapter (Fig. 1). The Launch Abort System (LAS) provides two functions; during nominal launches, the LAS provides protection for the Crew Module from atmospheric loads and heating during first stage flight and during emergencies provides a reliable abort capability for aborts that occur within the atmosphere. The Orion Launch Abort System (LAS) consists of an Abort Motor to provide the abort separation from the Launch Vehicle, an Attitude Control Motor to provide attitude and rate control, and a Jettison Motor for crew module to LAS separation (Fig. 2). The jettison motor is used during a nominal launch to separate the LAS from the Launch Vehicle (LV) early in the flight of the second stage when it is no longer needed for aborts and at the end of an LAS abort sequence to enable deployment of the crew module's Landing Recovery System. The LAS also provides a Boost Protective Cover fairing that shields the crew module from debris and the aero-thermal environment during ascent. Although the Orion Program has tested a number of the critical systems of the Orion spacecraft on the ground, the launch environment cannot be replicated completely on Earth. A number of flight tests have been conducted and are planned to demonstrate the performance and enable certification of the Orion Spacecraft. Exploration Flight Test 1, the first flight test of the Orion spacecraft, was successfully flown on December 5, 2014 from Cape Canaveral Air Force Station's Space Launch Complex 37. Orion's first flight was a two-orbit, high-apogee, high-energy entry, low-inclination test mission used to validate and test systems critical to crew safety, such as heat shield performance, separation events, avionics and software performance, attitude control and guidance, parachute deployment and recovery operations. One of the key separation events tested during this flight was the nominal jettison of the LAS. Data from this flight will be used to verify the function of the jettison motor to separate the Launch Abort System from the crew module so it can continue on with the mission. The LAS nominal jettison event on Exploration Flight Test 1 occurred at six minutes and twenty seconds after liftoff (See Fig. 3). The abort motor and attitude control motors were inert for Exploration Flight Test 1, since the mission did not require abort capabilities. A suite of developmental flight instrumentation was included on the flight test to provide data on spacecraft subsystems and separation events. This paper will focus on the flight test objectives and performance of the LAS during ascent and nominal jettison. Selected LAS subsystem flight test data will be presented and discussed in the paper. Exploration Flight Test -1 will provide critical data that will enable engineering to improve Orion's design and reduce risk for the astronauts it will protect as NASA continues to move forward on its human journey to Mars. The lessons learned from Exploration Flight Test 1 and the other Flight Test Vehicles will certainly contribute to the vehicle architecture of a human-rated space launch vehicle.

McCauley, R.↗

NASA NTRS2017

Vented Launch Vehicle Adaptor for a Manned Spacecraft with "Pusher" Launch Abort System

A system, method, and apparatus for a vented launch vehicle adaptor (LVA) for a manned spacecraft with a "pusher" launch abort system are disclosed. The disclosed LVA provides a structural interface between a commercial crew vehicle (CCV) crew module/service module (CM/SM) spacecraft and an expendable launch vehicle. The LVA provides structural attachment of the module to the launch vehicle. It also provides a means to control the exhaust plume from a pusher-type launch abort system that is integrated into the module. In case of an on-pad or ascent abort, which requires the module to jettison away from the launch vehicle, the launch abort system exhaust plume must be safely directed away from critical and dangerous portions of the launch vehicle in order to achieve a safe and successful jettison.

Vandervort, Robert E.↗

NASA NTRS2008

Design of Launch Abort System Thrust Profile and Concept of Operations

This paper describes how the Abort Motor thrust profile has been tailored and how optimizing the Concept of Operations on the Launch Abort System (LAS) of the Orion Crew Exploration Vehicle (CEV) aides in getting the crew safely away from a failed Crew Launch Vehicle (CLV). Unlike the passive nature of the Apollo system, the Orion Launch Abort Vehicle will be actively controlled, giving the program a more robust abort system with a higher probability of crew survival for an abort at all points throughout the CLV trajectory. By optimizing the concept of operations and thrust profile the Orion program will be able to take full advantage of the active Orion LAS. Discussion will involve an overview of the development of the abort motor thrust profile and the current abort concept of operations as well as their effects on the performance of LAS aborts. Pad Abort (for performance) and Maximum Drag (for separation from the Launch Vehicle) are the two points that dictate the required thrust and shape of the thrust profile. The results in this paper show that 95% success of all performance requirements is not currently met for Pad Abort. Future improvements to the current parachute sequence and other potential changes will mitigate the current problems, and meet abort performance requirements.

Litton, Daniel↗

NASA NTRS2015

Orion Launch Abort System Jettison Motor Performance During Exploration Flight Test 1

This paper presents an overview of the flight test objectives and performance of the Orion Launch Abort System during Exploration Flight Test-1. Exploration Flight Test-1, the first flight test of the Orion spacecraft, was managed and led by the Orion prime contractor, Lockheed Martin, and launched atop a United Launch Alliance Delta IV Heavy rocket. This flight test was a two-orbit, high-apogee, high-energy entry, low-inclination test mission used to validate and test systems critical to crew safety. This test included the first flight test of the Launch Abort System performing Orion nominal flight mission critical objectives. Although the Orion Program has tested a number of the critical systems of the Orion spacecraft on the ground, the launch environment cannot be replicated completely on Earth. Data from this flight will be used to verify the function of the jettison motor to separate the Launch Abort System from the crew module so it can continue on with the mission. Selected Launch Abort System flight test data is presented and discussed in the paper. Through flight test data, Launch Abort System performance trends have been derived that will prove valuable to future flights as well as the manned space program.

McCauley, Rachel J.↗

NASA NTRS2016

A Proposed Ascent Abort Flight Test for the Max Launch Abort System

The NASA Engineering and Safety Center initiated the Max Launch Abort System (MLAS) Project to investigate alternate crew escape system concepts that eliminate the conventional launch escape tower by integrating the escape system into an aerodynamic fairing that fully encapsulates the crew capsule and smoothly integrates with the launch vehicle. This paper proposes an ascent abort flight test for an all-propulsive towerless escape system concept that is actively controlled and sized to accommodate the Orion Crew Module. The goal of the flight test is to demonstrate a high dynamic pressure escape and to characterize jet interaction effects during operation of the attitude control thrusters at transonic and supersonic conditions. The flight-test vehicle is delivered to the required test conditions by a booster configuration selected to meet cost, manufacturability, and operability objectives. Data return is augmented through judicious design of the boost trajectory, which is optimized to obtain data at a range of relevant points, rather than just a single flight condition. Secondary flight objectives are included after the escape to obtain aerodynamic damping data for the crew module and to perform a high-altitude contingency deployment of the drogue parachutes. Both 3- and 6-degree-of-freedom trajectory simulation results are presented that establish concept feasibility, and a Monte Carlo uncertainty assessment is performed to provide confidence that test objectives can be met.

Tartabini, Paul V.↗

NASA NTRS2007

Launch Abort System Flight Test Overview

This viewgraph presentation is an overview of the Launch Abort System (LAS) for the Constellation Program. The purpose of the paper is to review the planned tests for the LAS. The program will evaluate the performance of the crew escape functions of the Launch Abort System (LAS) specifically: the ability of the LAS to separate from the crew module, to gather flight test data for future design and implementation and to reduce system development risks.

Williams-Hayes, Peggy↗

NASA NTRS2011

Max Launch Abort System (MLAS) Pad Abort Test Vehicle (PATV) II Attitude Control System (ACS) Integration and Pressurization Subsystem Dynamic Random Vibration Analysis

In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.

Ekrami, Yasamin↗

NASA NTRS2007

Crew Exploration Vehicle Launch Abort System Flight Test Overview

The Constellation program is an organization within NASA whose mission is to create the new generation of spacecraft that will replace the Space Shuttle after its planned retirement in 2010. In the event of a catastrophic failure on the launch pad or launch vehicle during ascent, the successful use of the launch abort system will allow crew members to escape harm. The Flight Test Office is the organization within the Constellation project that will flight-test the launch abort system on the Orion crew exploration vehicle. The Flight Test Office has proposed six tests that will demonstrate the use of the launch abort system. These flight tests will be performed at the White Sands Missile Range in New Mexico and are similar in nature to the Apollo Little Joe II tests performed in the 1960s. An overview of the launch abort system flight tests for the Orion crew exploration vehicle is given. Details on the configuration of the first pad abort flight test are discussed. Sample flight trajectories for two of the six flight tests are shown.

Williams-Hayes, Peggy S.↗

NASA NTRS2010

Air Data Boom System Development for the Max Launch Abort System (MLAS) Flight Experiment

Woods-Vedeler, Jessica A.↗

NASA NTRS2015

Orion Launch Abort System (LAS) Propulsion on Pad Abort 1 (PA-1)

This presentation provides a concise overview of the highly successful Orion Pad Abort 1 (PA-1) flight test, and the three rocket motors that contributed to this success. The primary purpose of the Orion PA-1 flight was to help certify the Orion Launch Abort System (LAS), which can be utilized in the unlikely event of an emergency on the launchpad or during mission vehicle ascent. The PA-1 test was the first fully integrated flight test of the Orion LAS, one of the primary systems within the Orion Multi-Purpose Crew Vehicle (MPCV). The Orion MPCV is part of the architecture within the Space Launch System (SLS), which is being designed to transport astronauts beyond low-Earth orbit for future exploration missions. Had the Orion PA-1 flight abort occurred during launch preparations for a real human spaceflight mission, the PA-1 LAS would have saved the lives of the crew. The PA-1 flight test was largely successful due to the three solid rocket motors of the LAS: the Attitude Control Motor (ACM); the Jettison Motor (JM); and the Abort Motor (AM). All three rocket motors successfully performed their required functions during the Orion PA-1 flight test, flown on May 6, 2010 at the White Sands Missile Range in New Mexico, culminating in a successful demonstration of an abort capability from the launchpad.

SLS↗

NASA NTRS2010

Guidance, Navigation and Control (GN and C) Design Overview and Flight Test Results from NASA's Max Launch Abort System (MLAS)

The National Aeronautics and Space Administration Engineering and Safety Center designed, developed and flew the alternative Max Launch Abort System (MLAS) as risk mitigation for the baseline Orion spacecraft launch abort system already in development. The NESC was tasked with both formulating a conceptual objective system design of this alternative MLAS as well as demonstrating this concept with a simulated pad abort flight test. Less than 2 years after Project start the MLAS simulated pad abort flight test was successfully conducted from Wallops Island on July 8, 2009. The entire flight test duration was 88 seconds during which time multiple staging events were performed and nine separate critically timed parachute deployments occurred as scheduled. This paper provides an overview of the guidance navigation and control technical approaches employed on this rapid prototyping activity; describes the methodology used to design the MLAS flight test vehicle; and lessons that were learned during this rapid prototyping project are also summarized.

Dennehy, Cornelius J.↗

NASA NTRS2010

GN and C Design Overview and Flight Test Results from NASA's Max Launch Abort System (MLAS)

The National Aeronautics and Space Administration (NASA) Engineering and Safety Center (NESC) designed, developed and flew the alternative Max Launch Abort System (MLAS) as risk mitigation for the baseline Orion spacecraft launch abort system (LAS) already in development. The NESC was tasked with both formulating a conceptual objective system (OS) design of this alternative MLAS as well as demonstrating this concept with a simulated pad abort flight test. The goal was to obtain sufficient flight test data to assess performance, validate models/tools, and to reduce the design and development risks for a MLAS OS. Less than 2 years after Project start the MLAS simulated pad abort flight test was successfully conducted from Wallops Island on July 8, 2009. The entire flight test duration was 88 seconds during which time multiple staging events were performed and nine separate critically timed parachute deployments occurred as scheduled. Overall, the as-flown flight performance was as predicted prior to launch. This paper provides an overview of the guidance navigation and control (GN&C) technical approaches employed on this rapid prototyping activity. This paper describes the methodology used to design the MLAS flight test vehicle (FTV). Lessons that were learned during this rapid prototyping project are also summarized.

Dennehy, Cornelius J.↗

NASA NTRS2010

Design and Analysis of Outer Mold Line Close-outs for the Max Launch Abort System (MLAS) Flight Experiment

In 2007, the NASA Exploration Systems Mission Directorate (ESMD) chartered the NASA Engineering Safety Center (NESC) to demonstrate an alternate launch abort concept as risk mitigation for the Orion project's baseline "tower" design. On July 8, 2009, a full scale, passive aerodynamically stabilized Max Launch Abort System (MLAS) pad abort demonstrator was successfully launched from NASA Goddard Space Flight Center's Wallops Flight Facility. Aerodynamic close-outs were required to cover openings on the MLAS fairing to prevent aerodynamic flow-through and to maintain the MLAS OML surface shape. Two-ply duct tape covers were designed to meet these needs. The duct tape used was a high strength fiber reinforced duct tape with a rubberized adhesive that demonstrated 4.6 lb/in adhesion strength to the unpainted fiberglass fairing. Adhesion strength was observed to increase as a function of time. The covers were analyzed and experimentally tested to demonstrate their ability to maintain integrity under anticipated vehicle ascent pressure loads and to not impede firing of the drogue chute mortars. Testing included vacuum testing and a mortar fire test. Tape covers were layed-up on thin Teflon sheets to facilitate installation on the vehicle. Custom cut foam insulation board was used to fill mortar hole and separation joint cavities and provide support to the applied tape covers. Flight test results showed that the tape covers remained adhered during flight.

Woods-Vedeler, Jessica A.↗

NASA NTRS2011

Reverse Launch Abort System Parachute Architecture Trade Study

This study investigated a potential Launch Abort System (LAS) Concept of Operations and abort parachute architecture. The purpose of the study was to look at the concept of jettisoning the LAS tower forward (Reverse LAS or RLAS) into the free-stream flow rather than after reorienting to a heatshield forward orientation. A hypothesized benefit was that due to the compressed timeline the dynamic pressure at main line stretch would be substantially less. This would enable the entry parachutes to be designed and sized based on entry loading conditions rather than the current stressing case of a Pad Abort. Ultimately, concerns about the highly dynamic reorientation of the CM via parachutes, and the additional requirement of a triple bridle attachment for the RLAS parachute system, overshadowed the potential benefits and ended this effort.

Litton, Daniel K.↗

NASA NTRS2011

Testing Strategies and Methodologies for the Max Launch Abort System

The National Aeronautics and Space Administration (NASA) Engineering and Safety Center (NESC) was tasked to develop an alternate, tower-less launch abort system (LAS) as risk mitigation for the Orion Project. The successful pad abort flight demonstration test in July 2009 of the "Max" launch abort system (MLAS) provided data critical to the design of future LASs, while demonstrating the Agency s ability to rapidly design, build and fly full-scale hardware at minimal cost in a "virtual" work environment. Limited funding and an aggressive schedule presented a challenge for testing of the complex MLAS system. The successful pad abort flight demonstration test was attributed to the project s systems engineering and integration process, which included: a concise definition of, and an adherence to, flight test objectives; a solid operational concept; well defined performance requirements, and a test program tailored to reducing the highest flight test risks. The testing ranged from wind tunnel validation of computational fluid dynamic simulations to component ground tests of the highest risk subsystems. This paper provides an overview of the testing/risk management approach and methodologies used to understand and reduce the areas of highest risk - resulting in a successful flight demonstration test.

Schaible, Dawn M.↗

NASA NTRS2011

Modeling, Analysis and Simulation Approaches Used in Development of the National Aeronautics and Space Administration Max Launch Abort System

The National Aeronautics and Space Administration (NASA) Engineering and Safety Center was chartered to develop an alternate launch abort system (LAS) as risk mitigation for the Orion Project. Its successful flight test provided data for the design of future LAS vehicles. Design of the flight test vehicle (FTV) and pad abort trajectory relied heavily on modeling and simulation including computational fluid dynamics for vehicle aero modeling, 6-degree-of-freedom kinematics models for flight trajectory modeling, and 3-degree-of-freedom kinematics models for parachute force modeling. This paper highlights the simulation techniques and the interaction between the aerodynamics, flight mechanics, and aerodynamic decelerator disciplines during development of the Max Launch Abort System FTV.

Yuchnovicz, Daniel E.↗